248 lines
6.7 KiB
C
248 lines
6.7 KiB
C
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/* $OpenBSD: dh_key.c,v 1.36 2018/11/12 17:39:17 tb Exp $ */
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/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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* All rights reserved.
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*
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* This package is an SSL implementation written
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* by Eric Young (eay@cryptsoft.com).
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* The implementation was written so as to conform with Netscapes SSL.
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*
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* This library is free for commercial and non-commercial use as long as
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* the following conditions are aheared to. The following conditions
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* apply to all code found in this distribution, be it the RC4, RSA,
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* lhash, DES, etc., code; not just the SSL code. The SSL documentation
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* included with this distribution is covered by the same copyright terms
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* except that the holder is Tim Hudson (tjh@cryptsoft.com).
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*
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* Copyright remains Eric Young's, and as such any Copyright notices in
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* the code are not to be removed.
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* If this package is used in a product, Eric Young should be given attribution
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* as the author of the parts of the library used.
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* This can be in the form of a textual message at program startup or
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* in documentation (online or textual) provided with the package.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* "This product includes cryptographic software written by
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* Eric Young (eay@cryptsoft.com)"
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* The word 'cryptographic' can be left out if the rouines from the library
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* being used are not cryptographic related :-).
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* 4. If you include any Windows specific code (or a derivative thereof) from
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* the apps directory (application code) you must include an acknowledgement:
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* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
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*
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* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* The licence and distribution terms for any publically available version or
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* derivative of this code cannot be changed. i.e. this code cannot simply be
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* copied and put under another distribution licence
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* [including the GNU Public Licence.]
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*/
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#include <stdio.h>
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#include <openssl/bn.h>
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#include <openssl/dh.h>
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#include <openssl/err.h>
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#include "bn_lcl.h"
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static int generate_key(DH *dh);
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static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh);
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static int dh_bn_mod_exp(const DH *dh, BIGNUM *r, const BIGNUM *a,
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const BIGNUM *p, const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
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static int dh_init(DH *dh);
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static int dh_finish(DH *dh);
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int
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DH_generate_key(DH *dh)
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{
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return dh->meth->generate_key(dh);
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}
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int
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DH_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
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{
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return dh->meth->compute_key(key, pub_key, dh);
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}
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static DH_METHOD dh_ossl = {
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.name = "OpenSSL DH Method",
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.generate_key = generate_key,
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.compute_key = compute_key,
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.bn_mod_exp = dh_bn_mod_exp,
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.init = dh_init,
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.finish = dh_finish,
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};
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const DH_METHOD *
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DH_OpenSSL(void)
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{
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return &dh_ossl;
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}
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static int
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generate_key(DH *dh)
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{
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int ok = 0;
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unsigned l;
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BN_CTX *ctx;
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BN_MONT_CTX *mont = NULL;
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BIGNUM *pub_key = NULL, *priv_key = NULL, *two = NULL;
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if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS) {
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DHerror(DH_R_MODULUS_TOO_LARGE);
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return 0;
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}
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ctx = BN_CTX_new();
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if (ctx == NULL)
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goto err;
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if ((priv_key = dh->priv_key) == NULL) {
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if ((priv_key = BN_new()) == NULL)
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goto err;
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}
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if ((pub_key = dh->pub_key) == NULL) {
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if ((pub_key = BN_new()) == NULL)
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goto err;
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}
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if (dh->flags & DH_FLAG_CACHE_MONT_P) {
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mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
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CRYPTO_LOCK_DH, dh->p, ctx);
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if (!mont)
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goto err;
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}
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if (dh->priv_key == NULL) {
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if (dh->q) {
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if ((two = BN_new()) == NULL)
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goto err;
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if (!BN_add(two, BN_value_one(), BN_value_one()))
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goto err;
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if (!bn_rand_interval(priv_key, two, dh->q))
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goto err;
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} else {
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/* secret exponent length */
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l = dh->length ? dh->length : BN_num_bits(dh->p) - 1;
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if (!BN_rand(priv_key, l, 0, 0))
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goto err;
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}
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}
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if (!dh->meth->bn_mod_exp(dh, pub_key, dh->g, priv_key, dh->p, ctx,
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mont))
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goto err;
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dh->pub_key = pub_key;
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dh->priv_key = priv_key;
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ok = 1;
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err:
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if (ok != 1)
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DHerror(ERR_R_BN_LIB);
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if (dh->pub_key == NULL)
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BN_free(pub_key);
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if (dh->priv_key == NULL)
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BN_free(priv_key);
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BN_CTX_free(ctx);
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BN_free(two);
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return ok;
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}
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static int
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compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
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{
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BN_CTX *ctx = NULL;
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BN_MONT_CTX *mont = NULL;
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BIGNUM *tmp;
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int ret = -1;
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int check_result;
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if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS) {
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DHerror(DH_R_MODULUS_TOO_LARGE);
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goto err;
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}
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ctx = BN_CTX_new();
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if (ctx == NULL)
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goto err;
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BN_CTX_start(ctx);
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if ((tmp = BN_CTX_get(ctx)) == NULL)
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goto err;
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if (dh->priv_key == NULL) {
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DHerror(DH_R_NO_PRIVATE_VALUE);
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goto err;
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}
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if (dh->flags & DH_FLAG_CACHE_MONT_P) {
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mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
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CRYPTO_LOCK_DH, dh->p, ctx);
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BN_set_flags(dh->priv_key, BN_FLG_CONSTTIME);
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if (!mont)
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goto err;
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}
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if (!DH_check_pub_key(dh, pub_key, &check_result) || check_result) {
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DHerror(DH_R_INVALID_PUBKEY);
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goto err;
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}
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if (!dh->meth->bn_mod_exp(dh, tmp, pub_key, dh->priv_key, dh->p, ctx,
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mont)) {
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DHerror(ERR_R_BN_LIB);
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goto err;
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}
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ret = BN_bn2bin(tmp, key);
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err:
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if (ctx != NULL) {
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BN_CTX_end(ctx);
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BN_CTX_free(ctx);
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}
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return ret;
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}
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static int
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dh_bn_mod_exp(const DH *dh, BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
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const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx)
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{
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return BN_mod_exp_mont_ct(r, a, p, m, ctx, m_ctx);
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}
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static int
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dh_init(DH *dh)
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{
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dh->flags |= DH_FLAG_CACHE_MONT_P;
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return 1;
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}
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static int
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dh_finish(DH *dh)
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{
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BN_MONT_CTX_free(dh->method_mont_p);
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return 1;
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}
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